Filtering Maven files into WEB-INF

<plugins>
    <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-war-plugin</artifactId>
        <version>2.0.2</version>
        <configuration>
            <webResources>
                <resource>
                    <directory>${basedir}/src/main/webapp/WEB-INF</directory>
                    <filtering>true</filtering>
                    <targetPath>WEB-INF</targetPath>
                    <includes>
                        <include>**/xmlgateway-context.xml</include>
                     </includes>
                </resource>
            </webResources>
        </configuration>
    </plugin>
</plugins>

Add the above to your pom.xml.
EDIT: Just to explain what the above conf is doing. With this added, mvn is going to filter files under src/main/webapp/WEB-INF and in particular filter the included files xmlgateway-context.xml and after filtering it is going to push the files in WEB-INF folder (thats what the target tag is saying).

Update if something is not clear.